1. Field of the Invention
The present invention relates to a display, and more particularly, it relates to a display including transistors.
2. Description of the Background Art
A display including transistors such as a liquid crystal display or an organic EL display is known in general. In this conventional display, transistors are provided on a pixel part as well as a peripheral circuit part arranged around the pixel part respectively. When external light or light from a backlight constituting the display is incident upon the transistors, the incident light may excite carriers in active layers of the transistors. In this case, current disadvantageously flows between the sources and the drains of the transistors due to the excited carriers also when the display holds the transistors in OFF-states. A display preventing incidence of light upon transistors of a pixel part and a peripheral circuit part by providing shielding films to cover the transistors for solving this problem is known in general, as disclosed in Japanese Patent Laying-Open No. 10-189999 (1998), for example. In this display, the shielding films covering the transistors unintentionally function as gate electrodes, to result in fluctuation of the threshold voltages of the transistors upon fluctuation of the potentials of the shielding films. This disadvantageously leads to instable operations of the transistors. Therefore, the display disclosed in the aforementioned Japanese Patent Laying-Open No. 10-189999 fixes the potentials of the shielding films to the ground potential, in order to suppress this disadvantage.
When the display disclosed in the aforementioned Japanese Patent Laying-Open No. 10-189999 supplies different signal potentials to the drain regions of the transistors provided on the pixel part and the peripheral circuit part respectively, the potentials of the channel regions of the transistors provided on the pixel part and the peripheral circuit part respectively may fluctuate to different levels due to electric fields resulting from the signal potentials applied to the drain regions also when the transistors are in OFF-states. If the display applies the common ground potential to the shielding films corresponding to all transistors provided on the pixel part and the peripheral circuit part respectively, the difference between the ground potential of the shielding film and the potential of the channel region of the corresponding transistor provided on the pixel part and that between the ground potential of the shielding film and the potential of the channel region of the corresponding transistor provided on the peripheral circuit part differ from each other, and hence either the difference between the ground potential of the shielding film and the potential of the channel region of the corresponding transistor provided on the pixel part or that between the ground potential of the shielding film and the potential of the channel region of the corresponding transistor provided on the peripheral circuit part may exceed the threshold voltage of the corresponding transistor. In this case, the transistor may enter an ON-state due to the ground potential supplied to the corresponding shielding film also when the display holds the transistor in an OFF-state. Consequently, the display may disadvantageously cause a malfunction.